Speaker
Description
Constraining variation in fundamental constants offers an important test for physics beyond the Standard Model.
The fine-structure constant (α) might not be constant throughout the universe. Models involving scalar fields coupled to α, the scalar charge depending on environment (e.g. on gravitational potential) naturally lead to α variation. White dwarf photospheres, where the gravitational potential can be ~10^5 times that on Earth, provide an important testbed of such ideas.
In atoms, different transitions have different sensitivities (q) to α variation (Δα/α), which results in a unique pattern of line shifts.
By comparing with laboratory wavelengths, Δα/α can be solved with Monte Carlo method.
In this project, we have used high resolution (R ~144,000) FUV spectra from white dwarf G191-B2B obtained with Hubble Space Telescope. A set of “clean”, unblended FeV absorption lines from photosphere were sampled for the analysis. To better quantify impact of uncertainties in laboratory wavelengths, 2 new experiments have been set to re-measure FeV UV wavelengths. A set of tests for systematics enables us to constrain uncertainties associated with q calculation, Zeeman and Stark shifts, and long-range wavelength distortion in spectrograph. Here we will present our new results and the first comprehensive analysis of systematic errors.
